Foreign material removing device and vehicle provided with this foreign material removing device

ABSTRACT

A foreign matter removal device ( 1 ) is configured to remove foreign matters on a lens ( 101 ) of an in-vehicle camera ( 100 ) attached to a vehicle so that the lens ( 101 ) of the in-vehicle camera ( 100 ) is exposed toward an outside of a body panel of the vehicle. The foreign matter removal device includes a single-cylinder type reciprocating pump ( 5 ) configured to generate high-pressure air and a nozzle ( 22 ) configured to inject the high-pressure air toward the lens ( 101 ). A volume of an internal space of the pump is 10 cm 3  or less. Exhaust time (t 1 ) per cycle required for exhausting the air in the internal space is 0.03 seconds or less.

TECHNICAL FIELD

The present invention relates to a foreign matter removal device forremoving foreign matters adhering to a lens of an in-vehicle camera byinjecting high-pressure air or the like from a nozzle, and a vehiclehaving the foreign matter removal device.

BACKGROUND ART

Recently, the number of vehicles equipped with in-vehicle cameras forphotographing the situations around the vehicle is increasing. In thein-vehicle cameras, there is a case that a lens as an imaging surfacebecomes dirty due to rain, mud or the like. Therefore, conventionally, aforeign matter removal device for removing foreign matters by blowingcleaning liquid or high-pressure air or the like to the lens of thein-vehicle camera in order to remove foreign matters such as waterdroplets adhering on the lens has been known (see Patent Document 1).

In such a foreign matter removal device, the performance of removingforeign matters may be deteriorated when the positioning accuracy of thetip end of the nozzle with respect to the lens of the camera is low.Therefore, for example, a structure has been proposed in which adedicated bracket for attaching a camera on a body panel of a vehicle isprovided, and a nozzle is positioned with respect to an upper surface ofa housing of a camera via the dedicated bracket (see Patent Document 2).

Further, Patent Document 1 discloses a configuration in which acompressed air generation unit is installed in the vicinity of anin-vehicle camera, compressed air generated by the compressed airgeneration unit is injected from a nozzle so that high-pressure air isblown to a front glass of the in-vehicle camera, thereby removing waterdroplets adhering to the front glass.

CITATION LIST Patent Document

Patent Document 1: Japanese Patent Laid-Open Publication No. 2001-171491

Patent Document 2: Japanese Patent Laid-Open Publication No. 2014-69586

DISCLOSURE OF INVENTION Problems to be Solved by Invention

In the case of removing foreign matters by blowing compressed air onto alens of a camera, means for temporarily increasing the wind speed bydecreasing an opening area of a nozzle or arranging a check valve in anair flow passage to accumulate pressure can be considered in order toincrease the flow velocity of air blown onto the lens. However, sincethe range where air can be blown onto the lens becomes narrow when theopening area of the nozzle is decreased, it is necessary to increase thesize of a pump. Further, when a check valve is mounted, a pump structurecapable of withstanding accumulated pressure is required, and thus, theconfiguration is complicated.

Further, in the configuration as disclosed in Patent Document 1, whencompressed air is generated by the compressed air generation unit, wateror the like may flow backward from a nozzle and enter the compressed airgeneration unit. Accordingly, there is a possibility that the compressedair generation unit is damaged or broken and compressed air with adesired pressure cannot be generated.

The present invention aims to provide a foreign matter removal devicewhich is capable of achieving the size reduction and simplification ofthe structure while maintaining the performance of removing foreignmatters and preventing the reverse flow of water or the like, and avehicle provided with the foreign matter removal device.

Means for Solving the Problems

The foreign matter removal device according to the present inventionremoves foreign matters on a lens of an in-vehicle camera attached to avehicle so that the lens of the in-vehicle camera is exposed toward theoutside of a body panel of the vehicle, the foreign matter removaldevice including:

a single-cylinder type reciprocating pump for generating high-pressureair; and

a nozzle for injecting the high-pressure air toward the lens,

in which a volume of an internal space of the pump is 10 cm³ or less,and the exhaust time per cycle required for exhausting the air in theinternal space is 0.03 s or less.

According to the above configuration, the air in the pump having a smallvolume of 10 cm³ or less can be instantaneously exhausted, and waterdroplets on the surface of the lens can be appropriately moved withoutcausing an increase in the volume of the pump, so that it is possible toachieve the compatibility between the maintaining of the foreign matterremoval performance and the size reduction of the device.

The flow rate of the pump may be 50 cm³/s or more during 0.02 s of theexhaust time required.

According to the above configuration, since the pump is used at a highflow rate region for a certain period of time, water droplets can bemore reliably removed.

The maximum flow rate in the exhaust per cycle of the pump may be 100cm³/s or more.

According to the above configuration, by setting the maximum flow rateto a certain value or more, water droplets can be more reliably removed.

The exhaust from the pump may be performed at least once per second.

According to the above configuration, by performing the exhaust from thepump a plurality of times in a short cycle, it is possible to quicklyremove water droplets newly adhering to the surface of the lens afterremoving water droplets without giving any discomfort to a driver.

An angle formed by a line passing through the center of an ejecting portof the nozzle and a tangential line of the apex of the lens may be 0° ormore but 60° or less.

The line passing through the center of the ejecting port of the nozzlemay intersect with a second region which is a second portion from thetop of the lens when the lens is divided into six equal parts in theupper and lower direction.

The pump may include a piston for feeding out the high-pressure air, anda spring for urging the piston in a feeding direction of thehigh-pressure air.

The pump may include a rack-and-pinion gear mechanism for allowing thepiston to slide according to the feeding direction.

The time during which the piston moves from the top dead center to thebottom dead center may be ten times or more the time during which thepiston moves from the bottom dead center to the top dead center.

According to these configurations, it is possible to more reliablyremove water droplets on the lens even in the case of the pump having asmall volume and a small power.

Further, the foreign matter removal device according to another exampleof the present invention removes foreign matters on a lens of a camera,the foreign matter removal device including:

a single-cylinder type reciprocating pump for generating high-pressureair; and

a nozzle for injecting the high-pressure air toward the lens,

in which a volume of an internal space of the pump is 10 cm³ or less,and the exhaust time per cycle required for exhausting the air in theinternal space is 0.03 s or less.

According to the above configuration, the air in the pump having a smallvolume of 10 cm³ or less can be instantaneously exhausted, and waterdroplets on the surface of the lens can be appropriately moved withoutcausing an increase in the volume of the pump, so that it is possible toachieve the compatibility between the maintaining of the foreign matterremoval performance and the size reduction of the device.

Further, the foreign matter removal device according to the presentinvention removes foreign matters adhering to a partition wallinterposed between an in-vehicle sensor and a measuring target of thein-vehicle sensor, the foreign matter removal device including

a single-cylinder type reciprocating pump for generating high-pressureair; and

a nozzle for injecting the high-pressure air toward the partition wall,

in which a volume of an internal space of the pump is 10 cm³ or less,and the exhaust time per cycle required for exhausting the air in theinternal space is 0.03 s or less.

The foreign matter removal device according to the present inventionremoves foreign matters on a lens of an in-vehicle camera attached to avehicle so that the lens of the in-vehicle camera is exposed toward theoutside of a body panel of the vehicle, the foreign matter removaldevice including:

a generation unit for generating high-pressure air;

a nozzle for injecting the high-pressure air toward the in-vehiclecamera; and

a piping connecting the generation unit and the nozzle,

in which the piping has a function of preventing the reverse flow ofwater.

According to the above configuration, the piping has the function ofpreventing the reverse flow of water. Therefore, even when water or thelike is introduced from the tip end of the nozzle at the time ofgenerating high-pressure air by the generation unit, it is possible toprevent the water from entering into the generation unit. As a result,it is possible to maintain the performance of removing foreign matterswithout causing the failure or breakage of the generation unit.

A volume of an internal space of the piping may be larger than a volumeof an internal space of the generation unit.

The generation unit may be constituted by a pump using a piston, and thevolume of the internal space of the piping may be larger than the volumeof the internal space of the pump.

According to these configurations, the volume of the internal space ofthe piping is larger than the volume of the internal space of thegeneration unit that, for example, is a pump. Therefore, it is possibleto reliably prevent the reverse flow of water or the like.

The generation unit may be arranged above the nozzle in the upper andlower direction of the vehicle.

According to the above configuration, it is possible to more reliablyprevent the reverse flow of water or the like.

The piping may have an intermediate portion which is located below oneend portion connected to the generation unit and the other end portionconnected to the nozzle in the upper and lower direction of the vehicle.

According to the above configuration, it is possible to more reliablyprevent water or the like from entering the generation unit.

Further, the foreign matter removal device according to another exampleof the present invention removes foreign matters on a lens of a camera,the foreign matter removal device including:

a generation unit for generating high-pressure air;

a nozzle for injecting the high-pressure air toward the lens; and

a piping connecting the generation unit and the nozzle,

in which the piping has a function of preventing the reverse flow ofwater.

According to the above configuration, the piping has the function ofpreventing the reverse flow of water. Therefore, even when water or thelike is introduced from the tip end of the nozzle at the time ofgenerating high-pressure air by the generation unit, it is possible toprevent the water from entering into the generation unit. As a result,it is possible to maintain the performance of removing foreign matterswithout causing the failure or breakage of the generation unit.

Further, the foreign matter removal device according to the presentinvention removes foreign matters adhering to a partition wallinterposed between an in-vehicle sensor and a measuring target of thein-vehicle sensor, the foreign matter removal device including

a generation unit for generating high-pressure air;

a nozzle for injecting the high-pressure air toward the partition wall;and

a piping connecting the generation unit and the nozzle,

in which the piping has a function of preventing the reverse flow ofwater.

Further, the vehicle of the present invention includes the foreignmatter removal device described above.

For example, even when a lens of an in-vehicle camera becomes dirty dueto rain, mud or the like, foreign matters on the lens can be removed byblowing compressed air thereto, thereby enhancing the accuracy ofinformation obtained from the in-vehicle camera.

Effects of Invention

According to the present invention, it is possible to provide a foreignmatter removal device which is capable of achieving the size reductionand simplification of the structure while maintaining the performance ofremoving foreign matters and preventing the reverse flow of water or thelike, and a vehicle provided with the foreign matter removal device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a rear view (a foreign matter removal device is shown in aperspective view) of a vehicle, FIG. 1B is a side view (the foreignmatter removal device is shown in a perspective view) of a rear part ofthe vehicle, and FIG. 1C is a partial enlarged view of the rear part ofthe vehicle.

FIGS. 2A and 2B are views showing another example of a position wherethe foreign matter removal device is attached.

FIG. 3 is a perspective view of a foreign matter removal deviceaccording to an embodiment of the present invention.

FIG. 4 is a configuration view of a high-pressure air generation unitincluded in the foreign matter removal device.

FIGS. 5A to 5C are image views of a flow rate-time curve ofhigh-pressure air generated by the high-pressure air generation unit andexhausted toward a nozzle.

FIGS. 6A and 6B are schematic configuration views showing a positionalrelationship between the nozzle included in the foreign matter removaldevice and a lens of an in-vehicle camera.

FIG. 7 is a flow rate-time graph according to Example 1 of high-pressureair exhausted from the high-pressure air generation unit.

FIG. 8 is a flow rate-pressure-time graph according to Example 1.

FIG. 9 is a flow rate-time graph according to Example 2 of high-pressureair exhausted from the high-pressure air generation unit.

FIG. 10 is a flow rate-pressure-time graph of air exhausted from a pumpaccording to a reference example.

FIG. 11 is a partial sectional view as seen from the side of the foreignmatter removal device.

FIG. 12 is a partial sectional view as seen from the side of the foreignmatter removal device shown in FIGS. 2A and 2B.

EMBODIMENT FOR CARRYING OUT INVENTION

Hereinafter, an example of an embodiment of the present invention willbe described in detail with reference to the drawings.

A foreign matter removal device of the present invention is applied as adevice for removing foreign matters such as water droplets, mud and dustadhering to a lens of an in-vehicle camera, for example.

As shown in FIGS. 1A and 1B, a foreign matter removal device 1 isattached to a back door 200A of a vehicle V, for example. The foreignmatter removal device 1 is provided with a drive unit 55, and a powersupply terminal of the drive unit 55 is connected to a power supply lineof a vehicle. For example, with the triggering that a gear of thevehicle V has entered the reverse, a vehicle control unit (ECU; notshown) causes an in-vehicle camera 100 (to be described later) to startphotographing, and the foreign matter removal device 1 is controlled tooperate by the vehicle control unit (ECU) within several seconds at thestart of photographing, for example.

The in-vehicle camera 100 is a camera for confirming, for example, therear side of the vehicle V and, as shown in FIG. 1C, a lens 101 of thein-vehicle camera 100 is attached to the back door 200A so that it isexposed toward the outside of the back door 200A of the vehicle V. Thein-vehicle camera 100 is provided with an imaging unit (not shown), andthe lens 101 covers the imaging unit. As the lens 101, a simpletranslucent cover that does not converge or diffuse light is alsoincluded in the lens of this example.

Meanwhile, as shown in FIGS. 2A and 2B, a foreign matter removal device1A may be attached to a rear bumper 200B of the vehicle V, for example.Meanwhile, the position at Which the in-vehicle camera 100 is attachedis not limited to the rear end side of the vehicle but may be a bodypanel such as the front side or lateral side of the vehicle. Further,the in-vehicle camera 100 may be attached to a vehicle body via avehicle mounted component such as a lamp, a door knob, a mirror, abumper attached to the body panel, or the in-vehicle camera 100 may bemounted as a part (as an integral body) of these components.

As shown in FIG. 3, the foreign matter removal device 1 includes anozzle unit 2, a joint member 3, a hose 4, and a high-pressure airgeneration unit 5.

The nozzle unit 2 is configured to be removably attached to thein-vehicle camera 100. The nozzle unit 2 includes an attachment part 21and a nozzle 22. The nozzle unit 2 is formed of resin material, forexample.

The attachment part 21 is attached to a housing 102 of the in-vehiclecamera 100 so as to cover a top surface of the in-vehicle camera 100.The nozzle 22 injects high-pressure air toward a lens 101 of thein-vehicle camera 100. The nozzle 22 is formed integrally with theattachment part 21. The nozzle 22 is provided in such a way that anejection port of the nozzle 22 faces the lens 101 when the attachmentpart 21 is attached to the housing 102. Here, the phrase, “formedintegrally with,” means that an operator can handle the nozzle 22 andthe attachment part 21 as an integral part during assembly work.Specifically, for example, the nozzle 22 and the attachment part 21 maybe molded of the same material and in the same mold. Alternatively, thenozzle 22 and the attachment part 21 may be respectively molded ofseparate materials, and then, fitted together and formed integrally,thereby constituting the nozzle unit 2.

The joint member 3 is a member for joining the nozzle 22 of the nozzleunit 2 and the hose 4. One end portion of the joint member 3 isconnected to the nozzle 22 and the opposite end portion thereof isconnected to the hose 4. The joint member 3 is formed of resin material,for example.

The hose 4 is a piping member that connects, together with the jointmember 3, the nozzle 22 and a high-pressure air generation unit 5. Oneend portion of the hose 4 is connected to the joint member 3 and theopposite end portion thereof is connected to a discharge port 50 of thehigh-pressure air generation unit 5. The hose 4 is formed of, forexample, a material such as resin or rubber.

The high-pressure air generation unit 5 is a unit for generatinghigh-pressure air to be fed to the nozzle 22, and is, for example, asingle-cylinder type reciprocating pump. The high-pressure airgeneration unit 5 is attached to a part of a vehicle body at the insideof a vehicle.

As shown in FIG. 4, the high-pressure air generation unit 5 includes acase body 51 and a moving mechanism disposed inside the case body 51. Ofa moving direction of a piston 52 in the high-pressure air generationunit 5, a rearward direction that is a direction of feeding out airrefers to a feeding direction, and a forward direction that is oppositeto the feeding direction refers to a force accumulation direction.

The high-pressure air generation unit 5 includes a piston 52 for feedingout high-pressure air, an urging spring 58 for urging the piston 52 in afeeding direction of the high-pressure air, and a rack-and-pinion gearmechanism for allowing the piston 52 to slide according to the feedingdirection of the high-pressure air. In an initial state beforehigh-pressure air is fed out, the piston 52 is positioned on the feedingdirection side by an urging force of the urging spring 58, and a rack 53is positioned in a state where a rack portion 53 a is engageable with agear portion 54 a of a pinion 54.

When the driving of the motor (drive unit) 55 is started and a drivingforce of the motor 55 is transmitted to a worm wheel 57 via a worm 56,the gear portion 54 a of the pinion 54 is meshed with the rack portion53 a of the rack 53. Therefore, the rack 53 moves in the forceaccumulation direction against an urging force of an urging spring 58 inaccordance with the rotation of the pinion 54. As the rack 53 moves inthe force accumulation direction, the meshing between the gear portion54 a and the rack portion 53 a is released at a predetermined position.The position (position shown in FIG. 4) where the meshing between thegear portion 54 a and the rack portion 53 a is released is set as thebottom dead center of the piston 52. In a state in which the piston 52is positioned at the bottom dead center, the air (outside air) flowinginto a substantially front half portion (second space) 60 b of aninternal space 60 of a piston support portion 59 passes through a gap 61b along a step 61 a and flows toward a substantially rear half portion(first space) 60 a of the internal space 60.

When the piston 52 is moved to the bottom dead center, the meshingbetween the gear portion 54 a and the rack portion 53 a is released, andthe piston 52 is moved in the feeding direction at a speed higher thanthe moving speed in the force accumulation direction by an urging forceof the urging spring 58. Meanwhile, the position where an end portion52A of the piston 52 is moved to an imaginary line L of the first space60 a is defined as the top dead center. In this way, the air flowingfrom the second space 60 b to the first space 60 a passes through thedischarge port 50 of a connection protrusion 62 from the first space 60a and is fed toward the nozzle 22 of the nozzle unit 2 via the hose 4.At this time, since the diameter of the discharge port 50 is smallerthan that of the piston support portion 59, the air discharged from thefirst space 60 a through the discharge port 50 is compressed intohigh-pressure air and is fed out.

In the present embodiment, a volume Vo of the internal space 60 of thepiston support portion 59 of the high-pressure air generation unit 5 is10 cm³ or less. The volume Vo is a volume of the first space 60 a in astate in which the piston 52 is positioned at the bottom dead center(see FIG. 4).

FIGS. 5A to 5C are image views of a flow rate-time curve ofhigh-pressure air generated by the high-pressure air generation unit 5and exhausted from a tip end of the nozzle 22 toward the lens 101 of thein-vehicle camera 100.

As shown in FIG. 5A, the high-pressure air generated by thehigh-pressure air generation unit 5 flows into the nozzle 22 and isexhausted from a tip end of the nozzle 22 toward the lens 101 of thein-vehicle camera 100. At this time, the maximum flow rate isrepresented as Q1 (cm³/s), and the time required for every exhaust isrepresented as t1(s). As a result of intensive study by the inventors,it has been found that the exhaust time t1(s) per cycle of the air inthe first space 60 a is desirably set to 0.03 seconds or less in orderto remove water droplets adhering on the lens 101 of the in-vehiclecamera 100 by using the small high-pressure air generation unit 5(single-cylinder type reciprocating pump) in which the volume Vo of theinternal space 60 of the piston support portion 59 is 10 cm³ or less.When the exhaust time t1(s) per cycle is longer than 0.03 seconds, it isdifficult to sufficiently secure the flow velocity or maximum flow rateQ1 of the high-pressure air, and therefore, it is difficult to properlyblow away water droplets adhering on the lens 101. Further, the maximumflow rate Q1 in the exhaust per cycle is preferably 100 cm³/s or more,more preferably 150 cm³/s or more. By setting the maximum flow rate Q1to 100 cm³/s or more, it is possible to reliably remove water dropletsor the like on the lens 101. Meanwhile, in FIG. 5A, the amount of airexhausted at the maximum flow rate Q1 within the exhaust time t1 percycle corresponds to the volume Vo of the first space 60 a of the pistonsupport portion 59.

Further, as shown in FIG. 5B, during a predetermined time t2(s) of theexhaust time t1(s) per cycle, it is preferable that high-pressure air isdiscarded so as to maintain a predetermined flow rate Q2 (cm³/s).Specifically, during at least 0.02 seconds (time t2) of the exhaust timet1 per cycle, it is preferable to exhaust the high-pressure air so thatthe flow rate Q2 of the high-pressure air becomes 50 cm³/s or more. Thereason is that, in order to remove water droplets, it is preferable toperform the exhaust for a certain time in a region where the flow rateof the high-pressure air generation unit 5 is somewhat high.

The high-pressure air generation unit 5 is controlled so as torepeatedly exhaust the high-pressure air. Preferably, the exhausting ofthe high-pressure air from the high-pressure air generation unit 5 isperformed at least once per one second. For example, as shown in FIG.5C, the exhaust interval t3(s) of the high-pressure air is set as thetime between the timings when the maximum flow rate of each exhaust timet1 is reached. By evacuating the high-pressure air generation unit 5 aplurality of times in a short cycle, it is possible to quickly removewater droplets newly adhering to the surface of the lens 101 afterremoving water droplets.

In FIG. 5C, the time during which the piston 52 in the high-pressure airgeneration unit 5 moves from the top dead center (a state in which theend portion 52A is located at the imaginary line L of the first space 60a) to the bottom dead center (a state shown in FIG. 4) is defined as aforce accumulation time t4(s), and the time during which the piston 52moves from the bottom dead center to the top dead center is defined asan exhaust time (feeding time) t1. At this time, as shown in FIG. 5C, itis preferable that the force accumulation time t4 is ten times or morethe feeding time t1. In this way, by slowly moving the piston 52 fromthe top dead center to the bottom dead center while instantaneouslymoving the piston 52 from the bottom dead center to the top dead center,that is, by instantaneously exhausting the air within the feeding timet1 while securing the force accumulation time t4 which is sufficientlylonger than the feeding time t1, it is possible to reliably move waterdroplets adhering to the lens 101 even in the high-pressure airgeneration unit 5 where an urging force of the urging spring 58 issmall.

As described above, the nozzle unit 2 is configured to be removablyattached to the in-vehicle camera 100. However, as shown in FIG. 6A,when an angle formed by a line C passing through the center of theejecting port 24 of the nozzle 22 and a tangential line of the apex ofthe lens 101 is defined as θ, the nozzle 22 is positioned with respectto the lens 101 so that the angle θ is 0° or more but 60° or less.Preferably, the angle θ is 5° or more but 30° or less. In this way, byarranging the ejecting port 24 of the nozzle 22 with respect to the lens101 while maintaining a predetermined slope, the high-pressure air canbe easily blown onto the entire surface of the lens 101, therebyenhancing the performance of removing water droplets. Meanwhile, in thecase where the lens mounted on the in-vehicle camera is a planar lens(e.g., plano-concave lens) instead of the curved lens 101 as in thepresent embodiment, a line along the surface of the planar lens isconsidered as the above tangential line, and the nozzle 22 may bepositioned with respect to the planar lens so that the angle θ formed bythe surface of the lens and the center line C of the ejecting port 24 ofthe nozzle 22 is 0° or more but 60° or less.

Further, as shown in FIG. 6B, when the lens 101 is divided into sixequal parts in the upper and lower direction, and a first region 101A, asecond region 101B, a third region 101C, a fourth region 101D, a fifthregion 101E and a sixth region 101F from the upper are defined, thecenter line C of the ejecting port 24 of the nozzle 22 intersects withthe second region 101B which is the second portion from the top of thelens 101. In this way, by positioning the ejecting port 24 of the nozzle22 toward a certain region (second region 101B) on the upper side of thelens 101, the high-pressure air can be easily blown onto the entiresurface of the lens 101, thereby enhancing the performance of removingwater droplets.

Next, an operation of the foreign matter removal device 1 will bedescribed with reference to FIGS. 3 and 4 again.

When the driving of the motor 55 in the high-pressure air generationunit 5 is started, first, air (outside air) for generating high-pressureair is sucked. The air is sucked into the high-pressure air generationunit 5 from the ejecting port 24 of the nozzle 22. The sucked air is fedout, as high-pressure air, from the discharge port 50 of thehigh-pressure air generation unit 5 to the hose 4 by piston motion dueto an urging force of the urging spring 58. The high-pressure air is fedfrom the hose 4 to the nozzle 22 of the nozzle unit 2 through the jointmember 3.

The high-pressure air flows into the nozzle 22, is injected from theejecting port 24 of the nozzle 22 and is blown toward the lens 101 ofthe in-vehicle camera 100 at a predetermined angle. The high-pressureair ejected from the ejecting port 24 is blown toward the lens 101 ofthe in-vehicle camera 100. In this way, foreign matters adhering to thelens 101 are blown away, so that the dirt of the lens 101 is eliminated.

EXAMPLE 1

FIG. 7 is a flow rate-time graph according to Example 1 of high-pressureair exhausted from the high-pressure air generation unit, and FIG. 8 isa flow rate-pressure-time graph according to Example 1. In Example 1,the high-pressure air generation unit having a volume Vo of 10 cm³ orless is used, and the nozzle having a tip end opening with a diameter ofφ1.2 mm is used.

As shown in FIGS. 7 and 8, in Example 1, the exhaust time per cycle isabout 10 ms (0.01 s), the maximum flow rate is about 275 cm³/s, and theexhaust interval is 550 ms. Further, the maximum pressure during theexhaust is about 80 kPa.

It was confirmed that water adhering on the lens can be appropriatelyremoved by evacuating the nozzle at the flow rate, the exhaust time, andthe exhaust interval shown in the flow rate-time graph of Example 1.

EXAMPLE 2

FIG. 9 is a flow rate-time graph according to Example 2 of high-pressureair exhausted from the high-pressure air generation unit. Also inExample 2, similar to Example 1, the high-pressure air generation unithaving a volume Vo of 10 cm³ or less is used, and the nozzle having atip end opening with a diameter of φ1.2 mm is used.

As shown in FIG. 9, in Example 2, the exhaust time per cycle is about 10ms (0.01 s) similar to Example 1, but the maximum flow rate is about 200cm³/s and the exhaust interval is 280 ms.

It was confirmed that water adhering on the lens can be appropriatelyremoved by evacuating the nozzle at the flow rate, the exhaust time, andthe exhaust interval shown in the flow rate-time graph of Example 2.Further, it can be confirmed that, by making the exhaust interval ofExample 2 shorter than Example 1, i.e., performing the exhaust morefrequently, the performance of removing foreign matters can bemaintained even when the maximum flow rate per cycle is suppressed lowerthan in Example 1.

Meanwhile, the necessary flow rate Q at the exhaust time t1 per cycle isobtained as follows.

For example, in an in-vehicle camera having a lens with a predeterminedouter diameter (e.g., 15 mm), assuming that the total amount of waterdroplets adhering to the surface of the lens is 3 cm³, the kineticenergy F for moving water of 3 cm³ on the lens by 15 mm is obtained bythe following equation (1).[Equation 1]F=μN×L=0.3×3(g)×15(mm)=0.135 mJ  (1)

Here, μ (coefficient of friction) is set to 0.3.

On the other hand, the energy W of air (wind) injected from the nozzletoward the lens is obtained by the following equation (2).

$\begin{matrix}{\mspace{79mu}\lbrack {{Equation}\mspace{14mu} 2} \rbrack} & \; \\{\mspace{79mu}{W = {\frac{1}{2}\rho\;{AV}_{3}}}} & (2) \\\{ \begin{matrix}{{\rho\text{:}\mspace{14mu}{air}\mspace{14mu}{density}} = {1.293\mspace{14mu}{kg}\text{/}m^{3}}} \\{{A\text{:}\mspace{14mu}{operating}\mspace{14mu}{area}} = {{opening}\mspace{14mu}{area}\mspace{14mu}{of}\mspace{14mu}{opening}\mspace{14mu}{portion}\mspace{14mu}{of}\mspace{14mu}{nozzle}}} \\{V\text{:}\mspace{14mu}{wind}\mspace{14mu}{velocity}}\end{matrix}  & \;\end{matrix}$

Here, A (the opening area of the ejecting portion of the nozzle) is setto 7.5 mm².

From the kinetic energy F obtained by the equation (1) and the energy Wof the air (wind) obtained by the equation (2), a wind velocity V formoving water of 3 cm³ on the lens by 15 mm is obtained by the followingequation (3). Meanwhile, at this time, the unit time t is 0.01 s.[Equation 3](0.135×10⁻³)/t=(1/2)×1.293·(7.5×10⁻⁸)×V ³  (3)(0.135×10⁻³)/t=(4.85×10⁻²)·V ²27.83/t=V ² t is set to 0.012783=V ²V=14(m/s)

Based on the wind velocity W obtained by the equation (3), the flow rateQ required for the high-pressure air generation unit is obtained by thefollowing equation (4).

$\begin{matrix}\lbrack {{Equation}\mspace{14mu} 4} \rbrack & \; \\\begin{matrix}{Q = {{V \cdot A} = {14\mspace{14mu}{( {m\text{/}s} ) \cdot ( {7.5 \times 10^{- 6}( m^{3} )} )}}}} \\{= {0.105 \times 10^{- 6}( {m^{3}\text{/}s} )}} \\{= {105\mspace{14mu}( {{cc}\text{/}s} )}}\end{matrix} & (4)\end{matrix}$

In this way, by appropriately setting the surface area of the lens, thetotal amount of water droplets adhering to the lens, the opening area ofthe nozzle, and the unit time or the like, the flow rate Q required forthe high-pressure air generation unit 5 in order to appropriately removewater droplets or the like adhering to the surface of the lens can beobtained. In the present embodiment, as a result of intensive study bythe inventors based on the necessary flow rate Q of the high-pressureair generation unit 5, a preferable range of the exhaust time t1, theexhaust interval t3 and the minimum required flow rate Q2 or the likehas been found in order to achieve the compatibility between the sizereduction of the high-pressure air generation unit 5 and the foreignmatter removal performance.

REFERENCE EXAMPLE

FIG. 10 is a flow rate-pressure-time graph of high-pressure airexhausted from a high-pressure air generation unit according to areference example. In the reference example, similar to Example 1, thenozzle having a tip end opening with a diameter of φ1.2 mm is used.

In the reference example, the exhaust time per cycle is about 200 ms(0.2 s), the maximum flow rate is about 125 cm³/s, and the pressureduring the exhaust is about 50 kPa. As shown in the reference example,conventionally the exhaust time per cycle is lengthened in order toremove water adhering on the lens, and the exhaust is performed at arelatively small flow rate. In this case, it is necessary to increasethe volume of the high-pressure air generation unit (e.g.,single-cylinder type reciprocating pump), and space saving cannot beachieved.

On the contrary, according to the foreign matter removal device 1 of thepresent embodiment, the high-pressure air generation unit 5 in which thevolume Vo of the internal space (first space) 60 a is 10 cm³ or less isused, and the high-pressure air is injected so that the exhaust time t1per cycle required for exhausting the air in the internal space 60 a is0.03 s or less. In this way in the present embodiment, the air in thehigh-pressure air generation unit 5 having a small volume of 10 cm³ orless is adapted to be instantaneously exhausted, and water droplets onthe surface of the lens 101 can be appropriately moved without causingan increase in the volume Vo of the high-pressure air generation unit 5,so that it is possible to achieve the compatibility between themaintaining of the foreign matter removal performance and the sizereduction of the device.

Further, according to the present embodiment, the exhaust form thehigh-pressure air generation unit is set so that the air flow rate Q2 ismaintained at 50 cm³/s or more during 0.02 s of the exhaust time t1. Inthis way, since the high-pressure air generation unit 5 is driven so asto maintain a high flow rate region for a certain period of time, waterdroplets can be more reliably removed.

Further, according to the present embodiment, the exhaust from thehigh-pressure air generation unit 5 is performed a plurality of times ina short cycle of at least one per second. Therefore, for example, it ispossible to quickly remove water droplets newly adhering to the surfaceof the lens 101 after removing water droplets without giving anydiscomfort to a driver.

Further, the foreign matter removal device of the present embodiment isconfigured such that the angle θ formed by the line C passing throughthe center of the ejecting port 24 of the nozzle 22 and the tangentialline of the apex of the lens 101 is 0° or more but 60° or less, and, thecenter line C of the ejecting port 24 of the nozzle 22 intersects withthe second region 101B which is the second portion from the top of thelens 101 when the lens 101 is divided into six equal parts in the upperand lower direction. Furthermore, the time (force accumulation time) t4when the piston 52 in the high-pressure air generation unit 5 is at thebottom dead center is ten times or more the time (exhaust time) t1 whenthe piston 52 is at the top dead center. With these configurations, itis possible to more reliably remove water droplets on the lens 101 evenwhen the high-pressure air generation unit 5 having a small volume and asmall power is used.

FIG. 11 is a partial sectional view as seen from the side of the foreignmatter removal device 1.

As shown in FIG. 11, in the foreign matter removal device 1, thehigh-pressure air generation unit 5 and the in-vehicle camera 100 towhich the nozzle unit 2 is attached are arranged such that thehigh-pressure air generation unit 5 is located above the nozzle unit 2in the upper and lower direction of the vehicle body. Then, the shape ofthe piston support portion 59 and the diameter and length of the hose 4are set such that a volume Vh of an internal space 43 of the hose 4 islarger than the volume Vo of the first space 60 a of the piston supportportion 59. Meanwhile, the volume Vo corresponds to the volume of thefirst space 60 a in a state (see FIGS. 3 and 4) in which the piston 52is located at the bottom dead center. In this way, the hose 4 connectingthe high-pressure air generation unit 5 and the nozzle unit 2 (jointmember 3) has a function of preventing the reverse flow of water.

By the way, when the driving of the drive motor in the high-pressure airgeneration unit 5 is started and air (outside air) for generatinghigh-pressure air is sucked from the tip end of the nozzle 22, water ormud or the like may be introduced from the tip end of the nozzle 22, andthese foreign matters may enter the high-pressure air generation unit 5.Therefore, conventionally, in addition to the hose (exhaust pipeline)connecting the nozzle and the high-pressure air generation unit that isan air pump, an intake pipeline is provided in the high-pressure airgeneration unit and a one way valve (check valve) is provided in each ofthe exhaust pipeline and the intake pipeline, thereby preventing wateror the like from entering the high-pressure air generation unit 5.

On the contrary, in the present embodiment, the volume Vh of theinternal space 43 of the hose 4 is larger than the volume Vo of thefirst space 60 a of the piston support portion 59. Therefore, even whenforeign matters such as water are introduced from the tip end of thenozzle 22 at the time of generating high-pressure air by thehigh-pressure air generation unit 5, it is possible to prevent foreignmatters from entering into the piston support portion 59 of thehigh-pressure air generation unit 5. As a result, the desiredhigh-pressure air can be generated without causing the failure orbreakage of the high-pressure air generation unit 5, and can be injectedfrom the nozzle 22 toward the lens 101. Further, since the high-pressureair generation unit 5 is located above the nozzle unit 2 in the upperand lower direction of the vehicle body, it is possible to more reliablyprevent the reverse flow of water or the like, and it is possible tomaintain the performance of removing foreign matters adhering to thelens 101 of the in-vehicle camera 100. Furthermore, an intake pipelinefor intake is provided in the high-pressure air generation unit 5 and awater reverse flow prevention mechanism can be provided without mountinga new component such as a check valve on the hose 4 or the intakepipeline, for example. In this way the configuration of the foreignmatter removal device 1 is very simple.

Next, modified examples of the foreign matter removal device 1 will bedescribed with reference to FIGS. 2 and 12.

As described above, as shown in FIGS. 2A and 2B, the foreign matterremoval device 1A may be attached to the rear bumper 200B of the vehicleV, for example. At this time, due to the structure of the vehicle, itmay be necessary to arrange the high-pressure air generation unit 5 soas to be located on the lower side of the vehicle body than thein-vehicle camera 100 to which the nozzle unit 2 is attached.

As shown in FIG. 12, a hose 4A of the foreign matter removal device 1Ahas an intermediate portion 44 which is located below a rear end portion41 connected to the joint member 3 and a front end portion 42 connectedto the high-pressure air generation unit 5 in the upper and lowerdirection of the vehicle. Further, from the rear end portion 41connected to the joint member 3, the hose 4A is temporarily disposed onthe upper side. And then, the hose 4A is bent in a substantially Ushape, and the front end portion 42 is connected to the high-pressureair generation unit 5. That is, the hose 4A is composed of a mountainportion 45 and a valley portion 46.

In this way when the high-pressure air generation unit 5 is arranged ata position lower than the nozzle 22, the hose 4A secures a volume of theinternal space 43 larger than the volume Vo of the first space 60 a ofthe piston support portion 59 at a position higher than the nozzle 22.That is, in the foreign matter removal device 1A, a volume Vh1 of theinternal space 43 from the rear end portion 41 of the hose 4A to aninflection point L1 where the hose 4A is inflected downward is set to belarger than the volume Vo of the first space 60 a of the piston supportportion 59. Therefore, even when the air in the hose 4A is sucked intothe piston support portion 59 at the time of generating high-pressureair by the high-pressure air generation unit 5, it is possible toprevent the water flowing backward from the tip end of the nozzle 22from flowing toward the high-pressure air generation unit 5 beyond themountain portion 45 of the hose 4A. In this way it is possible tomaintain the performance of the foreign matter removal device 1A.

Further, preferably the foreign matter removal device 1A is configuredsuch that a volume Vh2 of the internal space 43 from an inflection pointL2 where the hose 4A is inflected upward at the intermediate portion 44of the hose 4A to the front end portion 42 connected to thehigh-pressure air generation unit 5 is larger than the volume Vo of thefirst space 60 a of the piston support portion 59. According to thisconfiguration, for example, even when water enters the valley portion 46of the hose 4A from the nozzle 22, the water does not flow backward tothe inside of the high-pressure air generation unit 5, and thus, it ispossible to maintain the performance of the foreign matter removaldevice 1A.

Although the embodiments of the present invention have beenillustratively described above, the present invention is not limited tothese embodiments, and other configurations can be adopted as necessary.

In the above embodiments, the joint member 3 is provided as a member forjoining the nozzle 22 of the nozzle unit 2 and the hose 4. However, inthe case where there is no need to change the posture of the hose 4 withrespect to the nozzle 22, the hose 4 may be directly attached to thenozzle 22 without providing the joint member 3.

Further, in the above-described examples, the application to the camera(not limited to visible light) has been described. However, the sensorto which the present invention is applied is not limited to this. Thepresent invention may be applied to sensors attachable to vehicles, suchas LIDAE (laser radar), millimeter wave radars, and ultrasonic sensors.

Further, the target portion from which the foreign matter removal deviceremoves foreign matters is not limited to the lens of the camera. Forexample, the present invention can be applied to a foreign matterremoval device for removing foreign matters adhering on “partition wall”which is defined as a concept including an optical lens of a sensorelement, a cover for covering a front surface of an optical lens, acover for covering a vehicle mounted component such as a lamp having apart serving as a communication window of a sensor, a mirror, a bumper,a grill and a door knob, and a vehicle window when a sensor is mountedin a vehicle compartment. Meanwhile, this partition wall is not limitedto a transparent member (translucency), but may not be transparent in anultrasonic sensor, a millimeter wave radar or the like.

For example, in the above embodiments, the application of the foreignmatter removal device to the in-vehicle camera has been described.However, the object to which the present invention is applied is notlimited as long as it is a camera used outdoors. For example, a cameramounted so as to be exposed to the outside of an airplane, a railroad, aship, a robot, an outdoor installation object, a building and the likemay be included.

The present application is based on Japanese Patent Application (PatentApplication No. 2015-131789) filed on Jun. 30, 2015, and Japanese PatentApplication (Patent Application No. 2015-131790) filed on Jun. 30, 2015,the contents of which are incorporated herein by reference.

The invention claimed is:
 1. A foreign matter removal device,comprising: a single-cylinder type reciprocating pump configured togenerate high-pressure air; and a nozzle configured to suck airtherefrom into the single-cylinder type reciprocating pump and to injectthe high-pressure air toward a lens, wherein a volume of an internalspace of the pump is 10 cm³ or less, and exhaust time per cycle requiredfor exhausting the air in the internal space is 0.03 seconds or less,wherein flow rate of the pump is 50 cm³/s or more during 0.02 seconds ofthe exhaust time required.
 2. The foreign matter removal deviceaccording to claim 1, wherein exhaust from the pump is performed atleast once per second.
 3. The foreign matter removal device according toclaim 1, wherein an angle formed by a line passing through a center ofan ejecting port of the nozzle and a tangential line of an apex of thelens is 0° or more but 60° or less.
 4. The foreign matter removal deviceaccording to claim 1, wherein a line passing through a center of theejecting port of the nozzle intersects with a second region from a topof the lens when the lens is divided into six equal parts in upper andlower direction.
 5. The foreign matter removal device according to claim1, wherein the pump includes: a piston configured to feed out thehigh-pressure air; and a spring configured to urge the piston in afeeding direction of the high-pressure air.
 6. The foreign matterremoval device according to claim 5, wherein the pump includes arack-and-pinion gear mechanism configured to allow the piston to slideaccording to the feeding direction.
 7. The foreign matter removal deviceaccording to claim 5, wherein a first time during which the piston movesfrom a top dead center to a bottom dead center is ten times or more thanten times a second time during which the piston moves from the bottomdead center to the top dead center.
 8. A system comprising a lens of acamera and the foreign matter removal device according to claim 1,wherein the foreign matter removal device is configured to removeforeign matters on the lens of the camera.
 9. A system comprising apartition wall interposed between an in-vehicle sensor and a measuringtarget of the in-vehicle sensor and the foreign matter removal deviceaccording to claim 1, wherein the foreign matter removal device isconfigured to remove foreign matters adhering to the partition wallinterposed between the in-vehicle sensor and the measuring target of thein-vehicle sensor.
 10. A vehicle comprising the foreign matter removaldevice according to claim
 1. 11. A system comprising a lens of anin-vehicle camera attached to a vehicle and the foreign matter removaldevice according to claim 1, wherein the foreign matter removal deviceis configured to remove foreign matter from the lens of the in-vehiclecamera attached to the vehicle so that the lens of the in-vehicle camerais exposed toward an outside of a body panel of the vehicle.
 12. Aforeign matter removal device comprising: a single-cylinder typereciprocating pump configured to generate high-pressure air; and anozzle configured to suck air therefrom into the single-cylinder typereciprocating pump and to inject the high-pressure air toward a lens,wherein a volume of an internal space of the pump is 10 cm³ or less, andexhaust time per cycle required for exhausting the air in the internalspace is 0.03 seconds or less, wherein maximum flow rate of the pump inthe exhaust per cycle of 0.03 seconds or less is 100 cm³/s or more. 13.A system comprising a lens of a camera and the foreign matter removaldevice according to claim 12, wherein the foreign matter removal deviceis configured to remove foreign matters on the lens of the camera. 14.The foreign matter removal device according to claim 13, wherein flowrate of the pump is 50 cm³/s or more during 0.02 seconds of the exhausttime required.
 15. A system comprising a partition wall interposedbetween an in-vehicle sensor and a measuring target of the in-vehiclesensor and the foreign matter removal device according to claim 12,wherein the foreign matter removal device is configured to removeforeign matters adhering to the partition wall interposed between thein-vehicle sensor and the measuring target of the in-vehicle sensor. 16.A system comprising a lens of an in-vehicle camera attached to a vehicleand the foreign matter removal device according to claim 12, wherein theforeign matter removal device is configured to remove foreign matterfrom the lens of the in-vehicle camera attached to the vehicle so thatthe lens of the in-vehicle camera is exposed toward an outside of a bodypanel of the vehicle.